For this project, I have 916SP heads and I don't know at all if they are similar with 996 ones... For the external aspect, I would say yes...
I wasn't aware of the problem you told. I though that with 748R valve covers, it would be "easy".
Can you send some pics in order to understand well the problem?
You may have a pair of these covers available?
PS: for the 996RS triple injectors TB, it's a wonderful part .... I would like to put in my living room. But I think it may be a great challenge to set up correctly a 748R injection on a 955. So a RS one... I won't be competent enough
PS: I also have a set of 996RS triple injector throttle bodies (60mm) for sale. Those aren't going cheap though